1. Field of the Invention
The present invention relates to a reinforcing structure for reinforcing reinforced concrete piers in the civil engineering industry, the harbor industry and the building industry, and a method of reinforcing such reinforced concrete piers. More particularly, the present invention relates to a reinforcing structure for reinforcing reinforced concrete piers wrapped with high-performance, labor-saving steel plates which enhance the functions of earthquake-resisting hoops, and a method of reinforced concrete piers.
2. Description of the Related Art
Reinforced concrete piers which failed during the Kobe earthquake have taught that the hoop density, i.e., the number of hoops per unit length, of existing reinforced concrete piers is far less than that necessary to secure satisfactory earthquake resistance. Recently, a method of reinforcing existing reinforced concrete piers by wrapping the same with steel plates has been seen as prospective means for enhancing the earthquake resistance of existing reinforced concrete piers.
Referring to FIG. 24 showing a supplemental reinforcing structure for reinforcing an existing reinforced concrete pier, using wrapping steel plates, a reinforced concrete pier 52 provided with a plurality of longitudinal main reinforcing bars 50 and lateral hoops 51 is wrapped with steel plates with a space between the surface of the reinforced concrete pier and the steel plates. The steel plates includes flat steel plates 53 for covering flat portions of the surface of the reinforced concrete pier 52, and angular bent steel plates 54 having a cross section resembling the letter L, for covering the corner edge portions of the reinforced concrete pier 52. The respective edges of the flat steel plates 53 and the adjacent angular steel plates 54 are welded together by seam welding. The space between the reinforced concrete pier 52 and the steel plates 53 and 54 of the supplemental reinforcing structure is filled up with a freely formable hardening material 55, such as mortar. In FIG. 24, backing strips are indicated at 56.
This conventional supplemental reinforcing structure using the steel plates as shown in FIG. 24, however, is subject to circumferential tension, needs field seam welding and has the following disadvantages.
The reliability of the quality of welded portions of the steel plates of the supplemental reinforcing structure formed by seam welding at site is uncertain, field welding needs temporary work and large-scale scaffolding, requires troublesome work and increases costs.
The tendency of weld quality to deteriorate becomes more conspicuous if a corrosion-resistant metal, such as a stainless steel, or a high-strength steel is used.
If surface-treated steel plates, such as plated steel plates or coated steel plates, are used, corrosion proofing measures including pretreatment for the surface-preparation of the surfacing material in portions of the steel plates to be welded, and field posttreatment for touch-up painting and the like are necessary, and troublesome field work is unavoidable.